1. Chapter 12
Liquids and Solids

2. Sect. 12-1: Liquids Properties of liquids Definite volume
Takes shape of its container
Properties can be explained by the kinetic molecular theory (KMT) just like gases were explained
Fluid – has the ability to flow

3. Properties of liquids (con’t)
Relatively high density
Relative incompressibility
Ability to diffuse
Surface tension – force that tends to pull adjacent parts of a liquid’s surface together, thereby decreasing surface area to the smallest possible size

4. More properties of liquids…
Capillary action – the attraction of the surface of a liquid to the surface of a solid
Vaporization – liquid changes to a gas
Evaporation – vaporization occurring at the surface of a non-boiling liquid
Freezing – liquid changing to a solid

5. Sect. 12-2: Solids Properties of solids Definite volume Definite shape
Properties can be explained by the kinetic molecular theory (KMT) just like gases and liquids were explained

6. Two types of solids Crystalline solids – made up of crystals
Crystals – particles are arranged in an orderly, geometric fashion
Amorphous solids – particles are arranged randomly

7. More properties of solids…
Definite melting point – temperature at which a crystalline solid turns into a liquid
Supercooled liquids – substances that retain certain liquid properties even at temperatures at which they appear to be solid (amorphous solids)
High density
Incompressibility
Very low rate of diffusion

8. Crystalline solids
Crystal structure – total 3D arrangement of particles of a crystal
Unit cell – smallest part of a crystal structure that shows the 3D pattern of the entire structure

9. Binding forces in crystals
Ionic crystals
Covalent network crystals
Metallic crystals
Covalent molecular crystals

10. Sect.12-3: Changes of State
Equilibrium – a dynamic condition in which two opposing changes occur at equal rates in a closed system
Phase – any part of a system that has uniform composition and properties

11. Equilibrium and changes of state
If you start out with a closed container of liquid, eventually some of it will evaporate.
Over time, some of the gas will condense.
If left for a long enough period of time, equilibrium will be reached for amount of substance condensing vs. evaporating.
Represented by the following equation: liquid + heat energy  vapor

12. System will stay at equilibrium until some outside force acts upon it.
Le Châtelier’s Principle – when a system at equilibrium is disturbed by an application of stress, it attains a new equilibrium position that minimizes the stress
Stress is typically a change in concentration, pressure, or temperature.

13. Equilibrium and temperature
What will happen to earlier discussed liquid/vapor system if temperature is increased? Which reaction will be favored?
What if temp is decreased? Which reaction is favored?

14. Equilibrium and concentration
What would happen to system if volume of container was suddenly increased?
Amount of vapor would now be in lower concentration and thus less condensation would be occurring and more evaporation occurring until system reaches equilibrium again.
At the new equilibrium, there fewer liquid molecules, but the same concentration of the gas due to larger container size. (equilibrium has shifted right)

15. Equilibrium and Vapor Pressure of Liquid
Equilibrium vapor pressure – pressure exerted by a vapor in equilibrium over a liquid at a given temperature (increases as temp increases)
Explained by KMT
Pg. 376 for illustration

16. Volatile vs. nonvolatile liquids
Volatile liquid – liquids which evaporate very easily due to weak forces of attraction between particles
Have a relatively high equilibrium vapor pressure
Nonvolatile liquids have stronger forces of attraction and lower equilibrium vapor pressures

17. Boiling
Boiling – conversion of a liquid to a gas at the surface and throughout the liquid
Boiling point – temperature at which the equilibrium vapor pressure is equal to the atmospheric pressure
Pressure affects the boiling point
Normal boiling point is at 1 atm pressure

18. During a phase change, such as vaporization, the temperature remains constant because any heat being added is going to changing the particles from liquid to gas
Molar heat of vaporization – amount of heat required to vaporize one mole of liquid at its boiling point
The higher it is, the stronger the bonds are that hold that liquid together

19. Freezing and Melting
Freezing point – temperature at which the solid and liquid are in equilibrium at 1 atm
Molar heat of fusion – amount of heat required to melt one mole of a solid at its melting point

20. Sublimation – change of state from a solid directly to a gas
Deposition – change of state from a gas directly to a solid
Both occur at low pressures and temperatures where a liquid cannot exist

21. Phase Diagrams
Phase diagram – a graph of pressure vs. temperature that shows the conditions under which the phases of a substance exist

23. Triple point – indicates the temperature and pressure at which the solid, liquid, and vapor can coexist at equilibrium
Critical point – indicates critical temp. and pressure
Critical temperature (tc)– temp above which a substance cannot exist as a liquid
Critical pressure (Pc) – lowest pressure at which the substance can exist as a liquid at the critical temperature

24. Sect. 12-4: Water Water molecules have a bent structure
Solid or liquid water molecules are linked by hydrogen bonding
Ice is made up of water arranged in hexagon shapes; this allows for low density

25. Physical Properties of Water
Liquid water is odorless, tasteless, & transparent
Relatively high molar heat of fusion (6.009 kJ/mol)
Relatively high boiling point and molar heat of vaporization (40.79 kJ/mol) compared to other substances that have similar molar masses (because of hydrogen bonding)